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Isolation and Identification of Waterborne Antibiotic-Resistant Bacteria and Molecular Characterization of their Antibiotic Resistance Genes
Published on: March 3, 2023
Molecular Characterization of Aminoglycoside-modifying Enzymes (AMEs)in Aminoglycoside-Resistant Staphylococcus
Malihe Naderi1,2, Neda Yousefi Nojookambari3, Somayeh Talebi1
1Infectious Diseases Research Center, Golestan University of Medical Sciences, Gorgan, Iran.
Background & Objective:
The resistance genes encoding aminoglycoside-modifying enzymes (AMEs) are now widely prevalent in different populations of Staphylococcus aureus. The study aimed to determine the frequency of AMEs-encoding genes in clinical isolates of S. aureus.
Methods:
A total of 105 S. aureus isolates were obtained from the different clinical samples; and then were identified by conventional biochemical tests. The antibiotic resistance patterns of the isolates were characterized by the agar disk diffusion method. The distribution of the AMEs and femA genes was determined by conventional and multiplex PCR.
Results:
The aminoglycoside resistance rates of kanamycin, tobramycin, gentamicin, amikacin, and netilmicin were 47.6%, 46.6%, 45.7%, 45.7%, and 26.6%, respectively. 16.1% and 1.9% of isolates were MDR and XDR phenotypes, respectively. 21.9% of S. aureus isolates harbored the femA gene and were determined as methicillin-resistant S. aureus (MRSA) clones. The aac(6')/aph(2'') was the most prevalent (47.8%) AME-encoding gene in aminoglycoside-resistant S. aureus, followed by ant(4')-Ia (30.4%) and aph(3')-IIIa (21.7%).
Conclusion:
Our study demonstrated that the coexistence of several AMEs and the spread of the resistance determinants like femA in S. aureus clinical isolates are alarming and may contribute to the broadening of aminoglycoside resistance spectra and limit treatment options for staphylococcal infections.
Insights
Aminoglycoside resistance genes are common in Staphylococcus aureus clinical isolates. The study found high rates of resistance and prevalent AME genes, including aac(6')/aph(2'), raising concerns for treatment options.
Area of Science:
- Microbiology
- Molecular Biology
- Infectious Diseases
Background:
- Aminoglycoside-modifying enzyme (AME) encoding genes are increasingly prevalent in Staphylococcus aureus.
- Understanding the frequency of these resistance genes in clinical isolates is crucial.
Purpose of the Study:
- To determine the prevalence of AME-encoding genes in clinical Staphylococcus aureus isolates.
- To characterize antibiotic resistance patterns and identify specific resistance genes.
Main Methods:
- Conventional biochemical tests for S. aureus identification.
- Agar disk diffusion for antibiotic resistance profiling.
- Conventional and multiplex PCR for detecting AME and femA genes.
Main Results:
- High aminoglycoside resistance rates observed for kanamycin (47.6%), tobramycin (46.6%), gentamicin (45.7%), and amikacin (45.7%).
- The aac(6")/aph(2") gene was the most prevalent AME gene (47.8%), followed by ant(4">-Ia (30.4%) and aph(3">-IIIa (21.7%).
- The femA gene was present in 21.9% of isolates, associated with methicillin-resistant S. aureus (MRSA).
Conclusions:
- The widespread presence of AME genes and femA in S. aureus clinical isolates is concerning.
- This resistance can broaden aminoglycoside resistance and limit treatment options for staphylococcal infections.
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